There are two online resources that I tend to use to generate ideas for colour schemes.
The first is called Color Wizard. It is currently at version 3, and it allows you to specify a base colour. The site then shows you a series of colour swatches that suggest matching, contrasting and complementary colours.
It is very useful for sudden inspiration. You can find Color Wizard here.
Color Schemes 2
This site does essentially the same thing, although it claims to be using a different “more classical” way of interpreting colours. If you use Color Scheme 2 make sure to click on the help link which explains in some detail how it works. Without understanding this you won’t be able to use it effectively!